// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_TOUCH_SELECTION_TOUCH_HANDLE_H_
#define UI_TOUCH_SELECTION_TOUCH_HANDLE_H_

#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "ui/events/gesture_detection/motion_event.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/geometry/vector2d_f.h"
#include "ui/touch_selection/touch_handle_orientation.h"
#include "ui/touch_selection/touch_selection_draggable.h"
#include "ui/touch_selection/ui_touch_selection_export.h"

namespace ui {

class TouchHandle;

// Interface through which |TouchHandle| delegates rendering-specific duties.
class UI_TOUCH_SELECTION_EXPORT TouchHandleDrawable {
public:
    virtual ~TouchHandleDrawable() { }

    // Sets whether the handle is active, allowing resource cleanup if necessary.
    virtual void SetEnabled(bool enabled) = 0;

    // Update the handle visuals to |orientation|.
    // |mirror_vertical| and |mirror_horizontal| are used to invert the drawables
    // if required for adaptive handle orientation.
    virtual void SetOrientation(ui::TouchHandleOrientation orientation,
        bool mirror_vertical,
        bool mirror_horizontal)
        = 0;

    // Sets the origin position of the touch handle.
    // |origin| takes care of positioning the handle drawable based on
    // its visible bounds.
    virtual void SetOrigin(const gfx::PointF& origin) = 0;

    // Sets the transparency |alpha| for the handle drawable.
    virtual void SetAlpha(float alpha) = 0;

    // Returns the visible bounds of the handle drawable.
    // The bounds includes the transparent horizontal padding.
    virtual gfx::RectF GetVisibleBounds() const = 0;

    // Returns the transparent horizontal padding ratio of the handle drawable.
    virtual float GetDrawableHorizontalPaddingRatio() const = 0;
};

// Interface through which |TouchHandle| communicates handle manipulation and
// requests concrete drawable instances.
class UI_TOUCH_SELECTION_EXPORT TouchHandleClient
    : public TouchSelectionDraggableClient {
public:
    ~TouchHandleClient() override { }
    virtual void OnHandleTapped(const TouchHandle& handle) = 0;
    virtual void SetNeedsAnimate() = 0;
    virtual scoped_ptr<TouchHandleDrawable> CreateDrawable() = 0;
    virtual base::TimeDelta GetMaxTapDuration() const = 0;
    virtual bool IsAdaptiveHandleOrientationEnabled() const = 0;
};

// Responsible for displaying a selection or insertion handle for text
// interaction.
class UI_TOUCH_SELECTION_EXPORT TouchHandle : public TouchSelectionDraggable {
public:
    // The drawable will be enabled but invisible until otherwise specified.
    TouchHandle(TouchHandleClient* client,
        TouchHandleOrientation orientation,
        const gfx::RectF& viewport_rect);
    ~TouchHandle() override;

    // TouchSelectionDraggable implementation.
    bool WillHandleTouchEvent(const MotionEvent& event) override;
    bool IsActive() const override;

    // Sets whether the handle is active, allowing resource cleanup if necessary.
    // If false, active animations or touch drag sequences will be cancelled.
    // While disabled, manipulation is *explicitly not supported*, and may lead to
    // undesirable and/or unstable side-effects. The handle can be safely
    // re-enabled to allow continued operation.
    void SetEnabled(bool enabled);

    enum AnimationStyle { ANIMATION_NONE,
        ANIMATION_SMOOTH };
    // Update the handle visibility, fading in/out according to |animation_style|.
    // If an animation is in-progress, it will be overriden appropriately.
    void SetVisible(bool visible, AnimationStyle animation_style);

    // Update the focus points for the handles. The handle will be positioned
    // either |top| or |bottom| based on the mirror parameters.
    // Note: If a fade out animation is active or the handle is invisible, the
    // handle position will not be updated until the handle regains visibility.
    void SetFocus(const gfx::PointF& top, const gfx::PointF& bottom);

    // Update the viewport rect, based on which the handle decide its inversion.
    void SetViewportRect(const gfx::RectF& viewport_rect);

    // Update the handle visuals to |orientation|.
    // Note: If the handle is being dragged, the orientation change will be
    // deferred until the drag has ceased.
    void SetOrientation(TouchHandleOrientation orientation);

    // Ticks an active animation, as requested to the client by |SetNeedsAnimate|.
    // Returns true if an animation is active and requires further ticking.
    bool Animate(base::TimeTicks frame_time);

    // Get the visible bounds of the handle, based on the current position and
    // the drawable's size/orientation. If the handle is invisible or disabled,
    // the bounds will be empty.
    gfx::RectF GetVisibleBounds() const;

    // Updates the handle layout if the is_handle_layout_update_required_ flag is
    // set. Will be called once per frame update, avoids multiple updates for
    // for the same frame update due to more than one parameter updates.
    void UpdateHandleLayout();

    const gfx::PointF& focus_bottom() const { return focus_bottom_; }
    TouchHandleOrientation orientation() const { return orientation_; }

private:
    gfx::PointF ComputeHandleOrigin() const;
    void BeginDrag();
    void EndDrag();
    void BeginFade();
    void EndFade();
    void SetAlpha(float alpha);
    void SetUpdateLayoutRequired();

    scoped_ptr<TouchHandleDrawable> drawable_;

    TouchHandleClient* const client_;

    gfx::PointF focus_bottom_;
    gfx::PointF focus_top_;
    gfx::RectF viewport_rect_;
    TouchHandleOrientation orientation_;
    TouchHandleOrientation deferred_orientation_;

    gfx::PointF touch_down_position_;
    gfx::Vector2dF touch_drag_offset_;
    base::TimeTicks touch_down_time_;

    // Note that when a fade animation is active, |is_visible_| and |position_|
    // may not reflect the actual visibility and position of the drawable. This
    // discrepancy is resolved either upon fade completion or cancellation.
    base::TimeTicks fade_end_time_;
    gfx::PointF fade_start_position_;
    float alpha_;
    bool animate_deferred_fade_;

    bool enabled_;
    bool is_visible_;
    bool is_dragging_;
    bool is_drag_within_tap_region_;
    bool is_handle_layout_update_required_;

    // Mirror variables determine if the handles should be inverted or not.
    bool mirror_vertical_;
    bool mirror_horizontal_;
    float handle_horizontal_padding_;

    DISALLOW_COPY_AND_ASSIGN(TouchHandle);
};

} // namespace ui

#endif // UI_TOUCH_SELECTION_TOUCH_HANDLE_H_
